1. Field of the Invention
The present invention relates to a method of forming a plating film having a high aspect ratio (thickness/width) portion and a low aspect ratio portion, and a method of manufacturing a magnetic device using such a plating film and a method of manufacturing a perpendicular magnetic recording head using such a plating film.
2. Description of the Related Art
In the field of manufacturing various devices, the frame plating method has been widely used as a method of forming fine patterns. The frame plating method includes: forming a seed film as an electrode film on a surface of a substrate; forming a frame (a pattern film having an opening) on the seed film; and depositing a plating film on the seed film in the opening.
In the field of manufacturing various magnetic devices, improved frame plating method (namely, damascene method, and the like) has been used in order to form a fine pattern having a portion with an aspect ratio (thickness/width) greater than 1 (a high aspect ratio portion). In perpendicular magnetic recording head as an example of magnetic devices, this kind of fine pattern has a feature of leading magnetic flux to a magnetic recording medium, and is a magnetic pole layer and the like with a fine width portion defining a recording track width of the magnetic recording medium. The improved frame plating method includes: forming a pattern film having an opening on a surface of a substrate; forming a seed film so as to cover the pattern film and an exposed surface of the substrate in the opening; and depositing a plating film on the seed film in the opening. In the improved frame plating method, the plating film in the opening deposits not only on the seed film formed on the exposed surface of the substrate, but also on the seed film formed on an inner wall of the pattern film. Therefore, the entire plating film can be formed in a short time.
In particular in the field of manufacturing various magnetic devices, when a plating film is formed from a magnetic material, the plating film is deposited while applying a magnetic field in a direction along the surface of the substrate in order to obtain superior magnetic properties in the plating film (for example, soft magnetic properties with permeability as μ and retention as Hc). This is because, intersecting of the application direction of magnetic field with the deposit direction of the plating film leads to improvement of magnetic properties in the plating film as known by experience. In this case, the application direction of the magnetic field employs the same direction as the application direction of the magnetic field in the general frame plating method as forming the pattern film after forming the seed film.
In the improved frame plating method, some related techniques have been known already. Specifically, in the field of manufacturing semiconductor devices, the following method has been proposed to form plating films with uniform film thickness. A pair of magnets with semiconductor wafer in between are provided. Then a plating film is deposited while applying the magnetic field in the direction along a surface of the semiconductor wafer (for example, refer to Japanese Unexamined Patent Publication No. 2001-023932).
Generally in the field of plating, a plating device capable of changing the application direction of the magnetic field in a surface of a substrate has been proposed (for example, refer to Japanese Unexamined Patent Publication No. 2005-281797). With this device, a problem concerning arrangement of elements constituting the plating device has been eased. In the field of manufacturing the magnetic head, such a magnetic field application device has been proposed that magnets or magnetic materials were inserted in adjustment holes provided at a pair of rare earth magnets of convex cross section with a plating tub in between (for example, refer to Japanese Unexamined Patent Publication No.Hei-11-025424). With this device, a magnetic head with low noise has been achieved.